Image directed cerebrospinal fluid (CSF) flow determination method and system

ABSTRACT

In one aspect, the present disclosure describes a method for detecting cerebrospinal fluid (CSF) flow of a subject in which magnetic resonance imaging signals of a selected region of interest of the subject&#39;s anatomy are acquired. Preferably, the selected region of interest comprises the cerebro-spinal anatomy. A central location of the selected region of interest of the subject&#39;s anatomy is determined and used to determine a mean intensity value associated with image pixels of the central location. The mean intensity value is then used to establish interior and exterior outlines of the the selected region of interest of the subject&#39;s anatomy so that the CSF flow within the interior and exterior anatomical outlines may be measured or detected.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of the filing date of U.S.Provisional Patent Application No. 62/197,903 filed Jul. 28, 2015, thedisclosure of which is hereby incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to magnetic resonance imaging apparatus,systems and methods and procedures for improved quantification ofCerebro-Spinal Fluid (“CSF”) flow anywhere in the cerebro-spinalanatomy, e.g., within the ventricles, the cerebral acqueduct (oracqueduct of Sylvius), spinal canal, the sub-arachnoid space, theepidural space, the cerebello-medullary cistern, foramen of Monro,foramen of Magendie, foramen magnum, etc., i.e., where it is flowing.

BACKGROUND

In magnetic resonance imaging, an object to be imaged such as, forexample, a body of a human subject, is exposed to a strong,substantially constant static magnetic field. Radio frequency excitationenergy is applied to the body, and this energy causes the spin vectorsof certain atomic nuclei within the body to rotate or “precess” aroundaxes parallel to the direction of the static magnetic field. Theprecessing atomic nuclei emit weak radio frequency signals during therelaxation process, referred to herein as magnetic resonance signals.Different tissues produce different signal characteristics. Furthermore,relaxation times are the major factor in determining signal strength. Inaddition, tissues having a high density of certain nuclei will producestronger signals than tissues with a low density of such nuclei.Relatively small gradients in the magnetic field are superimposed on thestatic magnetic field at various times during the process so thatmagnetic resonance signals from different portions of the patient's bodydiffer in phase and/or frequency. If the process is repeated numeroustimes using different combinations of gradients, the signals from thevarious repetitions together provide enough information to form a map ofsignal characteristics versus location within the body. Such a map canbe reconstructed by conventional techniques well known in the magneticresonance imaging art, and can be displayed as a pictorial image of thetissues as known in the art.

The magnetic resonance imaging technique offers numerous advantages overother imaging techniques. MRI does not expose either the patient ormedical personnel to X-rays and offers important safety advantages. Inaddition, magnetic resonance imaging can obtain images of soft tissuesand other features within the body which are not readily visualizedusing other imaging techniques. Accordingly, magnetic resonance imaginghas been widely adopted in the medical and allied arts.

Several factors impose significant physical constraints in thepositioning of patients and ancillary equipment in MRI imaging. Many MRImagnets use one or more solenoidal superconducting coils to provide thestatic magnetic field arranged so that the patient is disposed within asmall tube running through the center of the magnet. The magnet and tubetypically extend along a horizontal axis, so that the long axis orhead-to-toe axis of the patient's body must be in a horizontal positionduring the procedure. Moreover, equipment of this type provides aclaustrophobic environment for the patient. Iron core magnets have beenbuilt to provide a more open environment for the patient. These magnetstypically have a ferromagnetic frame with a pair of ferromagnetic polesdisposed one over the other along a vertical pole axis with a gapbetween them for receiving the patient. The frame includes ferromagneticflux return members such as plates or columns extending verticallyoutside of the patient-receiving gap. A magnetic field is provided bypermanent magnets or electromagnetic coils associated with the frame. Amagnet of this type can be designed to provide a more open environmentfor the patient. However, it is still generally required for the patientto lie with his or her long axis horizontal.

Recently, ferromagnetic frame magnets having horizontal pole axes havebeen developed. As disclosed, for example, in commonly assigned U.S.Pat. Nos. 6,414,490 and 6,677,753, the disclosures of which areincorporated by reference herein, a magnet having poles spaced apartfrom one another along a horizontal axis provides a horizontallyoriented magnetic field within a patient-receiving gap between thepoles. Such a magnet can be used with a patient-positioning deviceincluding elevation and tilt mechanisms to provide extraordinaryversatility in patient positioning. For example, where the patientpositioning device includes a bed or similar device for supporting thepatient in a recumbent position, the bed can be tilted and/or elevatedso as to image the patient in essentially any position between a fullystanding position and a fully recumbent position, and can be elevated sothat essentially any portion of the patient's anatomy is disposed withinthe gap in an optimum position for imaging. As further disclosed in thepreviously mentioned patents, the patient positioning device may includeadditional elements such as a platform projecting from the bed tosupport the patient when the bed is tilted towards a standingorientation. Still other patient supporting devices can be used in placeof a bed in a system of this type. For example, a seat may be used tosupport a patient in a sitting position. Thus, magnets of this typeprovide extraordinary versatility in imaging.

Cerebrospinal fluid (“CSF”) is a clear body fluid found in the brain andspine. It provides mechanical and immunological protection to the brain,as well as cerebral autoregulation of cerebral blood flow. Whilereferences by ancient physicians, e.g., Hippocrates and Galen, to“water” or “liquid” surrounding or within the brain, suggest awarenessof CSF for millennia, in recent years its study has taken on renewedimportance. For example, in a Sep. 20, 2011 paper entitled “The PossibleRole of Cranio-Cervical Trauma and Abnormal C SF Hydrodynamics in theGenesis of Multiple Sclerosis” and published in Physiological Chemistryand Physics and Medical NMR, Vol. 41: 1-17, Damadian and Chu uncovered akey set of new observations regarding the possible relationship betweenCSF flow and Multiple Sclerosis (MS). In their work, Damadian and Chuconducted MRI studies of CSF flow in several patients observing that the“obstruction to CSF outflow would result in an increase in ventricularCSF pressure (ICP) which in turn could result in ‘leakage’ ofcerebrospinal fluid and its content . . . .” The importance ofunderstanding the relationship between CSF flow, velocity, volume, etc.and a variety of physical and/or neurological maladies cannot beoverstated. As such, systems and methods that can better enable thatunderstanding are extremely important to the medical profession.

As such, needs arise that require improvement in MRI technology,including software and related hardware. For example, while MRI capturestissue contrasts, improvements are needed to enable real timequantification of CSF flow in the cerebro-spinal anatomy.

SUMMARY

The present disclosure is directed to methods and system or apparatusthat detect and/or determine cerebrospinal fluid (CSF) flow within aselected region of anatomy. In one aspect, the method detects CSF flowof a subject. The method comprises acquiring magnetic resonance imagingsignals of a selected region of interest of the subject's anatomy, theselected region of interest comprising the cerebro-spinal anatomy;determining a central location of the cerebro-spinal anatomy; andprocessing the acquired magnetic resonance imaging signals to determinea mean intensity value associated with the cerebro-spinal anatomy bycalculating a three-by-three neighborhood average associated with imagepixels of the central location. This method may further comprisecomparing the mean intensity values to intensity values of pixels thatmake up the cerebro-spinal anatomy to determine interior and exterioranatomical outlines of the cerebro-spinal anatomy; and detecting the CSFflow within the interior and exterior anatomical outlines.

In another aspect a system is provided. The system comprises anapparatus for acquiring magnetic resonance imaging signals of a selectedregion of interest of the subject's anatomy, the apparatus having a pairof magnetic poles spaced apart along a horizontal direction parallel toa support surface of the apparatus, the magnetic poles configured tocreate a magnetic field in the horizontal direction, the apparatuscapable of accommodating the subject between the poles in an uprightposition; a memory storing instructions; a processor programmed usingthe instructions and configured to: receive the acquired magneticresonance signals, determine a center location of the selected region ofinterest of the subject's anatomy using the acquired magnetic resonancesignals, calculate a mean intensity value associated with the selectedregion of interest of the subject's anatomy using a three-by-threeneighborhood average associated with image pixels of the centerlocation, compare the mean intensity values to intensity values ofpixels that make up the selected region of interest of the subject'sanatomy to determine interior and exterior anatomical outlines of thesubject's anatomy, and measure the CSF flow within the interior andexterior anatomical outlines.

In another aspect a method for detecting and creating magnetic resonanceimaging anatomical outlines of a subject is provided. The methodcomprises acquiring magnetic resonance imaging signals of a selectedregion of interest of the subject's anatomy; processing the magneticresonance imaging signals to determine image pixel intensity of one ormore pixels associated with the selected region of interest; anddetermining anatomical outlines associated with the selected region ofinterest by comparing the image pixel intensity of the one or morepixels to a threshold value.

In yet another aspect a for determining cerebro-spinal fluid (CSF) flowof a subject is disclosed. The method comprises acquiring magneticresonance imaging signals of a selected region of interest of thesubject's anatomy; receiving as input to a computing device one or moreanatomical outlines that define a portion of the selected region;processing pixel intensity data of one or more pixels associated withthe portion of the selected region defined by the anatomical outlines todetermine a cross-sectional area; and determining anatomical outlinesassociated with the selected region of interest by comparing the imagepixel intensity of the one or more pixels to a threshold value.

One or more of the foregoing aspects may further comprise designatingpixels with intensity values 50% above the mean intensity value as partof the part of an interior anatomical outline or designating pixels withintensity values 25% below the mean intensity value as part of the partof an external anatomical outline.

In addition, the cerebro-spinal anatomy comprises the spinal cord andflowing CSF surrounding the spinal cord. Further still, thecerebro-spinal anatomy may be selected from the group consisting ofventricles, cerebral acqueduct (or acqueduct of Sylvius), spinal canal,the sub-arachnoid space, the epidural space, the cerebello-medullarycistern, foramen of Monro, foramen of Magendie, and foramen magnum.

In addition, the comparison may comprise comprises performing a radialsweep through the one or more pixels about the central location of thespinal cord.

Further still, the magnetic resonance imaging signals of the selectedregion of interest of the subject's anatomy may be acquired while thesubject is in an upright position. In this regard, the upright positionmay be selected from the group consisting of a sitting position and astanding position.

Further still, the pixels that make up the images may be derived fromT2-weighted magnetic resonance imaging signals.

In addition, determining further may comprise determining the outlines amean intensity value associated with the spinal cord by calculating athree-by-three neighborhood average of the one or more pixels associatedwith a central location of the spinal cord. Further still, determiningmay further comprise determining an anatomical outline around the spinalcord by comparing the image pixel intensity of the one or more pixelsassociated with the central location of the spinal cord with the meanintensity value.

Additionally, the method or system may further comprise displaying theselected region of interest as an image on a display or a display fordoing same. The anatomical outlines may then be drawn on the display andcomprise input to a processor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary MRI apparatus for imaging a subjectaccording to aspects of this disclosure.

FIG. 2A illustrates a system in accordance with an aspect of thisdisclosure.

FIG. 2B illustrates a networked system in accordance with an aspect ofthis disclosure.

FIG. 2C shows computing devices that may be used in accordance with anaspect of this disclosure.

FIG. 3 shows method steps in accordance with an aspect of thisdisclosure.

FIG. 4 shows a sample measurement made in accordance with an aspect ofthis disclosure.

DETAILED DESCRIPTION

The description to follow provides enabling but non-limiting examples ofthe various aspects of the present disclosure. From these non-limitingexamples one skilled in the art will appreciate that the disclosedmethods and systems may be modified without departing from the teachingsand scope of the claimed invention.

FIG. 1 illustrates an exemplary MRI apparatus 100 for imaging a subjectaccording to aspects of the disclosure. In one embodiment, the MRIapparatus 100 includes a magnet having a ferromagnetic frame 102, amagnetic flux generator 104, and a patient handling system 106. Theferromagnetic frame 102 includes a first side wall 108 and a second sidewall. The side walls extend vertically. As FIG. 1 is a sectional view ofthe MRI apparatus 100, FIG. 1 does not show the second side wall or anyof its associated structures for clarity. The second side wall wouldinclude all the components necessary to complete the path for a magneticcircuit or loop, e.g., a corresponding pole or an electromagnetic coilassembly to that shown in FIG. 1 with reference numeral 138, etc.

The ferromagnetic frame 102 may also include a top flux return structure112 and a bottom flux return structure 114. The top flux returnstructure 112 may include two columnar structures 116 and 118. Betweenthese two columnar structures, a top opening 120 is defined. Similarly,the bottom flux return structure 114 may include two columns 122 and 124that together define a bottom opening 126. Thus, the side walls and theflux return members 112 and 114 form a rectilinear structure, with thetop flux return structure 112 constituting the top wall of therectilinear structure, the bottom flux return structure 114 constitutingthe bottom wall of the rectilinear structure and the side walls formingthe side walls of the rectilinear structure. The frame 102 defines afront patient opening 128 on one side of the frame and a similar backpatient opening 130 on the opposite side of the frame.

The ferromagnetic frame further includes a first magnetic pole and asecond magnetic pole. The first magnetic pole extends from the firstside wall 108 towards the second side wall and the second magnetic poleextends from the second side wall towards the first side wall 108. Themagnetic poles are generally cylindrical and are coaxial with oneanother on a common horizontal polar axis. Between the magnetic poles isa gap accessed by the front patient opening 128, the back patientopening 130, the top opening 120 or the bottom opening 126.

The magnetic flux generator 104 includes a first electromagnetic coilassembly 138 magnetically coupled to ferromagnetic frame 102, proximateto side 108, and parallel to side 108. The magnetic flux generator 104also includes a second electromagnet coil assembly (not shown)magnetically coupled to ferromagnetic frame 102, proximate to the secondside wall, and parallel to the second side wall. As previously noted,these electromagnetic coil assemblies 138 and 140 may be eitherresistive or superconductive. Alternatively, the magnetic flux generator104 may be a permanent magnet. The magnetic flux generator 104 may beconfigured to emit a magnetic field B₀ along one or more axes. Themagnetic flux generator 104 may also include one or more gradient coils(not shown) for inducing a gradient in the B₀ magnetic field. The B₀magnetic field generally extends horizontally parallel to supportsurface of the apparatus from one side wall to the other. The supportsurface will generally be the floor of a building or facility housingthe apparatus 100.

The apparatus 100 may further include a patient support assembly 106including a chair or seat assembly 160 on which a patient is capable ofsitting. The patient handling system 106 is capable of three degrees ofmotion. The patient handling system further supports positioning of apatient in the Trendelburg and reverse-Trendleburg orientations.Generally, the degrees of motion allow for positioning of the patient ina variety of orientations or positions. The patient handling system 106may include a carriage 142 mounted on rails 144. The carriage 142 maymove linearly back and forth along the rails 144. The rails 144typically do not block the bottom open space 126.

A generally horizontal pivot axis is mounted on carriage 142. Anelevator frame 148 is mounted to the pivot axis. The carriage 142 isoperable to rotate the elevator frame 148 about the pivot axis. Apatient support 150 is mounted on the elevator frame 148. The patientsupport 150 may be moved linearly along the elevator frame 148 by anactuator 152. Thus, a patient 154 can be positioned with a total ofthree degrees of freedom, or along three axes of movement. Specifically,the patient handling system 106 can move a patient 154 in two lineardirections and also rotate patient 154 around an axis. The solid blackarrows of FIG. 1 show various axes of movement possible with the patienthandling system 106. Note that often the rails 108 are mounted such thatportions of patient 154 may be positioned below the rails through bottomopen space 126.

The apparatus 100 may be configured such that the seat assembly 160 isnot present. In that configuration, the patient would then be allowed tostand on the support 156. Allowing the patient to sit or stand, or moregenerally to remain in an upright position during image, has manyadvantages. For example, blood and CSF flow will be different in theupright position than in a recumbent position and may reveal. Inaddition, upright imaging of CSF flow may reveal abnormal conditions.

In making MRI measurements, the patient is fitted with an antenna coilthat receives magnetic resonance signals from the region of interest ofthe subject's anatomy being imaged. Such antennas are placed at on orproximate the patient and may include a variety of geometries thatmaximize the signal strength and signal-to-noise (S/N) ratios of themagnetic resonance signals emitted by the anatomy of interest. Suchantennas may include head coils to capture image signals associated withthe head, neck or upper spine. Other antennas may include coils that areplace proximate the back or spinal column. As another example, thepatient support assembly 106 may include a seat assembly 160 may includea quadrature coil arrangement. In particular, the seat assembly 160 mayinclude a seat or sitting surface 166, an enclosure 162 containing acontoured quadrature coil, and a cushion 164. The enclosure 162, whichis shown as being adjacent to patient 154, may then the contouredquadrature coil having a normal vector transverse to the horizontal poleaxis of the magnetic poles of the MRI apparatus 100, and thus transverseto the magnetic field vector parallel to the horizontal pole axis.

Additional views and disclosure of an MRI apparatus of the typediscussed above may be found by reference to U.S. Pat. No 6,677,753, thedisclosure of which is incorporated herein by reference. Alternativeembodiments of the MRI apparatus also include those discussed in U.S.Pat. No. 6,414,490, the disclosure of which is also incorporated byreference. In addition, the magnetic resonance image apparatus does notnecessarily need to include ferromagnetic frames or poles. For example,an apparatus such as that disclosed in commonly assigned U.S. Pat. No.8,384,387, the disclosure of which is incorporated by reference herein,may comprise the magnetic resonance imaging apparatus in accordance withthe various aspects of the present invention.

Turning now to FIG. 2A, there is shown a high level block diagram of asystem 200 that includes the apparatus 100 and a computing device 201.The computing device 201 is programmed using instructions that cause itto receive magnetic resonance imaging signals from the apparatus 100 andprocess those signals to determine an outline associated with theanatomy of interest, and use the outline to control detection and/ormeasurement of CSF flow in an area adjacent to the anatomy of interestor otherwise associated with the subject's anatomy.

The system 200 may be part of a computer network as shown in FIG. 2B.The illustration of FIG. 2B presents a schematic diagram of a computersystem depicting various computing devices that can be used alone or ina networked configuration in accordance with aspects of the invention.For example, this figure illustrates a computer network 260 having aplurality of computers 202, 204 and 206. The network 260 may includeother types of devices such as mobile phones or PDAs. Various elementsin the computer network 260 may be interconnected via a local or directconnection (such as shown in FIG. 2A) and/or may be coupled via acommunications network 216 such as a local area network (“LAN”), a WiFinetwork, a wide area network (“WAN”), the Internet, etc. and which maybe wired or wireless. The communications network 216 may include aplurality of nodes having routers, servers, wireless access points, etc.

Each computing device can include, for example, one or more computershaving user inputs such as a keyboard and mouse and/or various othertypes of input devices such as pen-inputs, joysticks, buttons, touchscreens, etc., as well as a display, which could include, for instance,a CRT, LCD, plasma screen monitor, TV, projector, etc. Each computer202, 204 and 206 may be a personal computer, server, etc. By way ofexample only, computer 202 may be a desktop computer, while computer 204may be a server, and computer 206 may be a laptop. As shown in FIG. 2Ceach computer, such as computers 202 and 204, contains a processor 224,memory 226 and other components typically present in a computer.

With continued reference to FIG. 2C, memory 226 stores informationaccessible by processor 224, including instructions 228 that may beexecuted by the processor 224 and data 230 that may be retrieved,manipulated or stored by the processor. The memory may be of any typecapable of storing information accessible by the processor, such as ahard-drive, ROM, RAM, CD-ROM, DVD, Blu-Ray disk, flash memories,write-capable or read-only memories. The processor 224 may comprise anynumber of well known processors, such as processors from IntelCorporation. Alternatively, the processor may be a dedicated controllerfor executing operations, such as an ASIC.

The instructions 228 may comprise any set of instructions to be executeddirectly (such as machine code) or indirectly (such as scripts) by theprocessor. In that regard, the terms “instructions,” “steps” and“programs” may be used interchangeably herein. The instructions may bestored in any computer language or format, such as in object code ormodules of source code. The functions, methods and routines ofinstructions in accordance with the present invention are explained inmore detail below.

Data 230 may be retrieved, stored or modified by processor 224 inaccordance with the instructions 228. The data may be stored as acollection of data. For instance, although the invention is not limitedby any particular data structure, the data may be stored in computerregisters, in a relational database as a table having a plurality ofdifferent fields and records, XML documents, or flat files. Map-typeimage data may be stored in flat files such as keyhole flat files(“KFF”). Content and advertising data may be stored in one or morerelational databases.

The data may also be formatted in any computer readable format such as,but not limited to, binary values, ASCII etc. Similarly, the data mayinclude images stored in a variety of formats such as vector-basedimages or bitmap images using lossless (e.g., BMP) or lossy (e.g., JPEG)encoding. Moreover, the data may include any information sufficient toidentify the relevant information, such as descriptive text, proprietarycodes, pointers, references to data stored in other memories (includingother network locations) or information which is used by a function tocalculate the relevant data.

Although the processor 224 and memory 226 are functionally illustratedin FIG. 2C as being within the same block, it will be understood thatthe processor and memory may actually comprise multiple processors andmemories that may or may not be stored within the same physical housingor location. For example, some or all of the instructions and data maybe stored on a removable recording medium such as a CD-ROM, DVD orBlu-Ray disk. Alternatively, such information may be stored within aread-only computer chip. Some or all of the instructions and data may bestored in a location physically remote from, yet still accessible by,the processor. Similarly, the processor may actually comprise acollection of processors which may or may not operate in parallel. Datamay be distributed and stored across multiple memories 126 such as harddrives, data centers, server farms or the like.

In one aspect, the computing device 204 comprises a server. The othercomputing devices 202, 206 computer may be a general purpose computer,intended for use by a person, having all the components normally foundin a personal computer such as a central processing unit (“CPU”),display, CD-ROM, DVD or Blu-Ray drive, hard-drive, mouse, keyboard,touch-sensitive screen, speakers, microphone, modem and/or router(telephone, cable or otherwise) and all of the components used forconnecting these elements to one another.

The server and computers are capable of direct and indirectcommunication with other computers, such as over network 216. Thenetwork 216, including any intervening nodes, may comprise variousconfigurations and protocols including the Internet, intranets, virtualprivate networks, wide area networks, local networks, private networksusing communication protocols proprietary to one or more companies,Ethernet, WiFi, Bluetooth and HTTP.

Communication across the network, including any intervening nodes, maybe facilitated by any device capable of transmitting data to and fromother computers, such as modems (e.g., dial-up or cable), networkinterfaces and wireless interfaces. Server 204 may be an applicationserver such as a web server.

Although certain advantages are obtained when information is transmittedor received as noted above, other aspects of the invention are notlimited to any particular manner of transmission of information. Forexample, in some aspects, the information may be sent via a medium suchas a disk, tape, CD-ROM, DVD, Blu-Ray disk or directly between twocomputer systems via a dial-up modem. In other aspects, the informationmay be transmitted in a non-electronic format and manually entered intothe system.

The networked architecture 260 shown in FIG. 2B provides someflexibility in implementing the system. For example, the more complexprocessing may be done on the server 204, while the computer 202 may beused to control the actual acquisition of magnetic resonance signalsfrom the apparatus 100. For example, the server may, in accordance withthe discussions below, process the magnetic resonance signals itreceives from computer 202 to identify the anatomy of interest andcerebro-spinal anatomy and then instruct the the computer 202 to performmeasurements of the CSF using the identified anatomy of interest andcerebro-spinal anatomy. Alternatively, the system may be simplifiedarchitecturally as shown in FIG. 2A with only a computer, such ascomputer 204, more directly connected to the apparatus 100 andperforming all the analysis, while at the same time controlling theapparatus 100.

Databases 1 and 2 are preferably used to store patient data, such asimages resulting from MRI scans. The databases may also be used to storeother data, as well as the computer code or instructions that the serverand/or computers use to perform the measurements and methods disclosedherein.

In accordance with an aspect of the present invention, thosemeasurements and methods include a software capability that detects andconstructs outlines of anatomy of interest that allow for accurate andreproducible identification of anatomies of interest and measurement ofCSF flow. Phase-contrast MRI pulse sequences provides the capability tovisualize and measure the flow of CSF. The phase-contrast pulse sequencecreates images with pixel intensities that correspond to flow rates.Conversion factors may be used to convert pixel intensity in MRI imagesinto absolute CSF flow rates. In addition to flow rates, volume andpressure gradient of the CSF may also be computed based on the pixelintensity. Conventional programs rely on the user drawing outlinesaround the CSF to determine CSF flow. Using these programs it is oftenvery difficult, at the very first level, to identify the outlines of theanatomical region of interest that defines the CSF flow channel. Inaddition, even where an inaccurate outline is drawn, it is notreproducible.

In a method in accordance with the present invention, a portion of thecerebro-spinal anatomy of a subject is selected for magnetic resonanceimaging. The cerebro-spinal anatomy may include any one of theventricles, the cerebral acqueduct (or acqueduct of Sylvius), spinalcanal, the sub-arachnoid space, the epidural space, thecerebello-medullary cistern, foramen of Monro, foramen of Magendie,foramen magnum, etc., i.e., anywhere that CSF is flowing. Once theregion of interest of the cerebro-spinal anatomy is selected, e.g., by auser, a phase contrast MRI pulse sequence is then acquired of the regionusing apparatus 100. Next, a center point or central location within theregion of interest is identified. Using the center point or centrallocation, the intensity of image pixels resulting from the phasecontrast scan is then compared to intensity thresholds to determine theinterior and exterior outlines of the region of interest bordering theCSF flow. Once the outlines are determined, the CSF flow can bedetermined using conversion factors that convert pixel intensity intoflow rates for those pixels within the region defined by the outlines.

In a more specific example as shown in FIG. 3, the method is explainedwith the region of interest being the spinal canal. Typically, thesemeasurements are preferably made at the mid-C-2 vertebra of the spine,but may also be made elsewhere with appropriate modification. Asexplained above, the method begins with a phase-contrast pulse sequencescan of the spinal canal, block 310. Next, the center of the spinal cordis selected, block 320. This selection may be done by a user orpreferably can be done via software using the intensity thresholdalgorithms described below. Next, based on pixel intensity thresholding,a first outline is created and placed around the spinal cord and secondoutline is created that defines the external border of the CSF region ofthe spinal canal, block 330. FIG. 4 shows an example of how intensitythreshold is used to create outlines around the spinal cord and thesurrounding CSF. The plot on the left corresponds to the outlines thedesignating the spinal cord and the CSF region. The plot on the rightcorresponds to the horizontal line in the left image.

Returning now to FIG. 3, once the outlines are created, they define aregion that identifies the CSF. Once this region is identified, a phasecontrast flow analysis uses the intensity values within the CSF regionto calculate flow rates, velocity, volume and pressure gradient of theCSF, block 340. The details of the techniques for such an analysis maybe found by reference to the following article, which is incorporated byreference herein: Sep. 20, 2011 paper entitled “The Possible Role ofCranio-Cervical Trauma and Abnormal C SF Hydrodynamics in the Genesis ofMultiple Sclerosis” and published in Physiological Chemistry and Physicsand Medical NMR, Vol. 41: 1-1. Such techniques involve a frame-by-framemotion analysis of pixels within a region. These measurements may becalculated and displayed soon after, e.g., from a few seconds to severalminutes (10-15 minutes), the scan. Alternatively, they may be stored,e.g., in the databases mentioned above, and then later processed at theserver or other computing device mentioned above.

In another aspect, the method may proceed as follows. An MRItechnologist (MRI “tech”) will first cursor “click” the center of thespinal cord in this example. Next, a first outline is created and placedaround the spinal cord and a second outline is created that defines theexternal border of the CSF in the spinal canal. The outlines arepreferably created automatically using software incorporating themethodology described herein. The two outlines will then define the CSFpresent in spinal canal. Sitting, “real time” at the MRI console the MRI“tech” will then position the MRI image “cursor” at the external borderof the spinal canal and upon cursor activation (“cursor click”) themagnetic resonance imaging system will measure and/or compute the CSFflow (cc/sec) and CSF velocity (cm/sec) of the CSF under examination,e.g., in this case inside the spinal canal. But the same measurement,under “tech” and cursor designation will then be “real time” measured inany CSF channel, e.g., the cerebral aqueduct. This will enable themeasurement, real time CSF flow pre-op and immediately post-op to assurethat the surgical procedures utilized, e.g., neuro-surgical,art-biopedic and neurologic have not compromised CSF flow. The CSFmeasurements are preferably made both in a recumbent and uprightposition. In accordance with this aspect of the invention, a computingdevice, such for example the desktop/laptop 202 of FIGS. 2B and 2C,would be configured to receive input from a user or “MRI tech.” Theinput may include the user drawing anatomical outlines on the spinalanatomy that define, for example, the outlines of the spinal cord andCSF around the spinal cord. The desktop/laptop may then further processthis input to determine the cross-sectional area defined by the outline,e.g., the area between the inner and outer borders shown in FIG. 4. Oncethe cross sectional area is determined (e.g., in units of cm²) the CSFflow may be computed based on the cross-sectional area and a measure ofCSF velocity within that area. The measure of CSF may be determined froma separately run scan, which measures the velocity or rate at which flowenters and exit, e.g., in cm/second, a predetermined cylindrical spacesurrounding the spinal cord. Thus, in accordance with this aspect oncethe input is received from a user, the software program (as described infurther detail below) may thereafter perform the tasks for actualdetermination of CSF flow. As such, the process would begin with receiptof the user input by the software algorithm.

As discussed above, in one aspect the outlines defining the region ofinterest is done using software that carries out an intensity thresholdalgorithm. The software algorithm is colloquially referred to as theCSFROI program. In the case of the spinal canal, the algorithm uses acentral point in the spinal cord, which is inside the region of intereston an axial view, to determine the outer and inner borders of the regionof interest. It uses intensity thresholds to determine the interior andexterior CSF boundaries in a radial sweep around the central point inthe cord. This works best on T2-weighted images because they providehigh intensity pixels from CSF with low intensity pixels from the cordand other tissues. This algorithm uses a three-by-three pixelneighborhood average of the entire image to reduce the noise level. Italso uses a three-by-three neighborhood average around the central cordpoint to obtain the mean cord intensity. The intensity threshold forinterior region of interest is 50 percent above the cord's mean. Theintensity threshold for the exterior ROI is 25 percent below the peakCSF intensity. These thresholds were determined empirically from patientstudies with T2 and phase contrast axial images at the mid-C2 vertebralocation. Intensity thresholds may vary depending the type of scan aswell as the region of interest. The radial sweep steps by five degreesin a full 360 degrees around the central cord point. See FIG. 4 for atypical intensity profile.

A three-by-three neighborhood average smoothes out pixel intensities byaveraging each value with its surrounding values. The “three by three”phrase describes the matrix dimensions around each pixel that was usedfor the average. This technique improves the Signal to Noise Ratio (SNR)at the expense of resolution. The resulting image will appear blurrier,but increases edge detection accuracy. An example of a three—by threeaverage is as follows. Original pixel value and surroundings:

$\begin{matrix}{\quad 2} & 3 & 7 \\{\quad 2} & 4 & 6 \\{\quad 0} & 1 & 2\end{matrix}$

The central pixel value changes from 4 to the average value(2+3+7+2+4+6+0+1+2)/9=3. The same three-by-three average is used for themean cord intensity. It is “around” the pixel that was clicked on withthe mouse. Depending on the quality of the scan and type of scan, otheraveraging techniques may be used. For example, if the scan is noisier, a4×4 thresholding technique may prove more useful. In contrast, a lessnoisier scan may use a 2×2 thresholding or no thresholding at all.

In general, the method can work on any other anatomy. However, becauseof variations in the shape, intensity, and signal to noise of otheranatomy, the above parameters or algorithms may need to be modified. Forexample, for the CSF determination, the program uses a 50 percentincrease to enter the CSF from the cord, and a 25 percent decrease toexit the CSF. These thresholds may differ for blood vessels. The edgedetection algorithm for CSF may not work for more irregularly shapedobjects, such as the ventricles. These changes may be determinedempirical via MRI measurements or theoretically.

Other components of the system include an image display (IDS) program.The IDS program provides the user interface for identifying the CSFregion and obtaining flow measurements. It allows for display of the T2and phase-contrast images, preferably in stack mode. Stack mode involveslooking at an image from each scan (or separate acquisitions)side-by-side, e.g., a T2 next to a phase contrast. It allows foridentification of the central cord point on the T2. The IDS will createa data file with the image file name and central cord point'scoordinates. The IDS will then run the CSFROI program with this inputfile. The CSFROI program determines the ROI points as described aboveand writes their coordinates to the same data file. The IDS then readsthe ROI points and displays both ROIs. It then uses the ROIs to create adata file with information from the CSF pixel intensities in thephase-contrast image series. A phase contrast flow analysis (PCFA)program creates data files with the analysis results and produces asummary with the key measurements.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

The invention claimed is:
 1. A method for detecting cerebrospinal fluid(CSF) flow of a subject, comprising: acquiring a plurality of magneticresonance imaging signals of a selected region of interest of thesubject's anatomy, the selected region of interest comprising acerebro-spinal anatomy; receiving an indication of a central location ofthe cerebro-spinal anatomy, wherein the central location is in thesubject's spinal cord; processing the acquired magnetic resonanceimaging signals to determine a respective intensity value for each imagepixel of a plurality of image pixels within the cerebro-spinal anatomy;determining a mean intensity value for the image pixels associated withthe central location of the cerebro-spinal anatomy; determining aninterior anatomical outline of the cerebro-spinal anatomy based onrespective intensity values of image pixels outside of the centrallocation exceeding the mean intensity value by at least a firstthreshold amount, wherein a perimeter of the interior anatomical outlineencloses the central location on an axial view of the selected region ofinterest; determining an exterior anatomical outline of thecerebro-spinal anatomy based on the respective intensity values of imagepixels outside of the central location being less than the meanintensity value by at least a second threshold amount, wherein aperimeter of the exterior anatomical outline encloses the interioranatomical outline on the axial view of the selected region of interest;and detecting the CSF flow between the interior and exterior anatomicaloutlines.
 2. The method of claim 1, wherein the first threshold amountis 50%.
 3. The method of claim 1, wherein the second threshold amount is25%.
 4. The method of claim 1, wherein the cerebro-spinal anatomyincludes any one or combination of ventricles, cerebral acqueduct (oracqueduct of Sylvius), spinal canal, the subarachnoid space, theepidural space, the cerebello-medullary cistern, foramen of Monro,foramen of Magendie, and foramen magnum.
 5. The method of claim 1,wherein determining each of the interior anatomical outline and theexterior anatomical outline is performed by evaluating image pixelsoutside of the central location in a sequence according to a radialsweep around the central location.
 6. The method of claim 1, whereinacquiring the plurality of magnetic resonance imaging signals of theselected region of interest of the subject's anatomy is conducted whilethe subject is in an upright position.
 7. The method of claim 6, whereinthe upright position is selected from the group consisting of a sittingposition and a standing position.
 8. The method of claim 1, furthercomprising: computing a measure of CSF velocity for the cross-sectionalarea based on the CSF flow detected between the interior and exterioranatomical outlines.
 9. The method of claim 8, wherein the interior andexterior anatomical outlines define the subject's spinal canal.
 10. Themethod claim 8, further comprising displaying the selected region ofinterest as an image on a display.
 11. The method of claim 10, whereinthe anatomical outlines are displayed on the display, and wherein theimage on the display comprises the central location.
 12. The method ofclaim 1, wherein determining the mean intensity value comprisescalculating a three-by-three neighborhood average associated with imagepixels of the central location, and wherein determining an intensityvalue of a given pixel comprises calculating a three-by-threeneighborhood average of the given pixel.
 13. A system for measuringcerebrospinal fluid (CSF) flow of a subject, comprising: an apparatusfor acquiring a plurality of magnetic resonance imaging signals of aselected region of interest of the subject's cerebro-spinal anatomy, theapparatus having a pair of magnetic poles spaced apart along ahorizontal direction parallel to a support surface of the apparatus, themagnetic poles configured to create a magnetic field in the horizontaldirection, the apparatus capable of accommodating the subject betweenthe poles in an upright position; a memory storing instructions; aprocessor programmed using the instructions and configured to: receivethe acquired magnetic resonance signals, receive an indication of acenter location of the selected region of interest of the subject'sanatomy, wherein the center location is in the subject's spinal cord,for each given image pixel of a plurality of image pixels within theselected region of interest, determine an intensity value of the givenpixel based on the acquired magnetic resonance signals, calculate a meanintensity value associated with the center location, determine aninterior anatomical outline of the cerebro-spinal anatomy based on theintensity values of the given image pixels outside of the centerlocation exceeding the mean intensity value by at least a firstthreshold amount, wherein a perimeter of the interior anatomical outlineencloses the center location on an axial view of the selected region ofinterest, determine an exterior anatomical outline of the subject'scerebro-spinal anatomy based on the intensity values of the given imagepixels outside of the interior anatomical outline being less than themean intensity value by at least a second threshold amount, wherein aperimeter of the exterior anatomical outline encloses the interioranatomical outline on the axial view of the selected region of interest,and detect the CSF flow between the interior and exterior anatomicaloutlines.
 14. The system according to claim 13, wherein thecerebro-spinal anatomy includes any one or combination of ventricles,cerebral acqueduct (or acqueduct of Sylvius), the spinal cord, spinalcanal, the sub-arachnoid space, the epidural space, thecerebello-medullary cistern, foramen of Monro, foramen of Magendie, andforamen magnum.
 15. The system according to claim 13, wherein theapparatus is configured to accommodate the subject in at least one of anupright sitting position and an upright standing position between thepoles.
 16. The system according to claim 13, wherein the processor isconfigured to: determine the intensity value of the given pixel bycalculating a three-by-three neighborhood average of the given pixel;determine the mean intensity value by calculating a three-by-threeneighborhood average associated with image pixels of the centerlocation.